Pneumatic control system



June 25, 1940. c. A. OTTO 2,205,930

' PNEUMATIC CONTROL SYSTEM 57 53 L 22 TO counmox'uns 56 5% APPARATUS 413 54 32 57 44 4s 42L I 3 39 2s 1 31- 46 i y/K4 i 15 1 2e W117 0 "as 50Q9 7 81 "19- -5 Mamie: MA N @ClfZ/E u (Ittomegs June 25, 1940.

C. A. OTTO PNEUMATIC CONTROL SYSTEM 2 Sheets-Sheet 2 Filed Feb. 27, 1939MAIN AIR TO CONDITION NG APPAKATU S 'ro CONDITIONING 83 APPARATUS 75Zhwantor MCLOMO &4&, ,7.

attorneys Patented June 25, 1940 I UNITED STATES 2,205,930 PNEUMATICCONTROL SYSTEM Carl A. om, Milwaukee, Wis. asaignor to John- 1 sonService Company, Milwaukee, Wis., a corporation of Wisconsin ApplicationFebruary '27, 1939, Serial No. 258,804

'1 Claims.

This invention relates to pneumatic control.

systems, and more particularly to pneumatic telemetering systemsdesigned to coordinate the readjustment of a recording instrument with 5changes in the setting orv adjustment of an associated conditioning orother apparatus for controlling a variable physical quantity.

In the prior art electrical telemetering systems have been used forindicating various physical conditions at a point remote from that wheresuch condition is sensed or controlled. Such electric systems are highlydeveloped and function efiectively in relations where electric circuitscan be employed safely and without adversely affecting installationsalready in existence. In certain locations, such for example as in theoperating rooms of hospitals, where explosion hazards exist. it becomesunsafe to use electric controlling circuits for telemetering. Inasmuchas penumatic control apparatus, particularly as applied to the controlof temperature and humidity, is highly developed and in commen use, itbecomes desirable to utilize such existing apparatus as a telemeteringmeans which offers no explosion hazards.

While pneumatic telemetering systems have been proposed, prior artschemes have been faulty either because of the highly sensitivecharacter of the apparatus requiring careful adjustment and frequentservicing, or because the response of the indicating apparatus was sosluggish as to make the mechanism impractical.

The present invention proposes to, remedy existing faults in pneumatictelemetering systems, and to accomplish substantially all the resultswhich are characteristic of electric telemetering systems, with none ofthe disadvantages.

In pneumatic apparatus of the type to which the present inventionrelates, it is usual to employ branch line pressures which vary fromzero to'fifteen pounds per square inch. In order to obtain suflicientsensitiveness in such systems so that controlled apparatus may havesubstantial pressure available for operation, the means pro} vided mustbe such that the slight changes in the condition or quantity sensedshall produce substantial changes in branch line pressures. The presentinvention accomplishes this result for the first time as applied topenumatic telemetering systems and, for purposes of illustration, theinvention will be described as applied to conditioning apparatus. It isto be understood, however, that it may findapplication to thetelemetering'oi temperature, pressure, relative humidity and. otherphysical conditions, atmospheric or otherwisarequiring accurateindications at a point remote from the point where such condition issensed or controlled.

In the drawings, the present invention has been illustrated as appliedto telemeteringsys- 6 tems associated with air conditioning apparatus inwhich a factor such as temperature ,is' to be sensed, and a record madeat a point remote from the point where such quantity is sensed.

Figure 1 shows one form of apparatus em- 10 bodying the invention, andwherein the mechanism for varying the control point ofthe sensing deviceand simultaneously readjusting the recording instrument is located at apoint away from both the instrument and the sensing device, 16 thevarious instruments being shown in section so as to show their interiorconstruction.

Fig. 2 is a modified form of the invention in which the device forvarying the control point is logated in proximity to the recordinginstr'ugo men Fig. 3 is a further modification in which the device forvarying the control point is associated withthe sensing device; and

Fig. 4' is a partial section of the control point adjusting device shownin'Fis. 3.

In Fig. 1 of the drawings, the invention is illustrated as applied to asystem in which conditioning apparatus, for example, apparatus forcontrollingthe temperature of the atmosphere within an enclosure, isconnected to recording apparatus located at a remote point and arrangedto give a continuous accurate indication of just whattemperature theconditioning apparatus is supplying. As indicated above, theconditioning or equivalent apparatus may be used to control quantitiesother than tempera- .ture, but for purposes of the present descriptionit has been assumed that temperature is the factor under control.

As illustrated in Fig. 1, the source of pressure fluid designated .mainair' supplies pressure fluid such as compressed air to a plurality ofunits, namely a pressure controlling valve A, a remote controlthermostat B having an associ- 5 ated relay, and a recording device'Q Inthe arrangement of Fig. 1, it will be assumed that the device B with itsrelay is located in the vicinity of the conditioning apparatus to becontrolled, while the device A is located at a point remote from boththe controlling instrument B and the recording instrument 0.

The instrument B may take a variety of forms, but for purposes of thisdescription it will be described as comprising'a so-called intermediateacting thermostat such, for example, as that described in the patent toOtto, No. 2,009,675, granted July 30, 1935. Such instruments may becaused to operate from a main line pressure of fifteen pounds per squareinch and to deliver branch line pressures varying from zero to M- teenpounds per -square inch. The pressure in the branch line of suchinstruments is a function of the deviation of the temperature from acertain predetermined value which may be conveniently referred to as thesetting point or control point of the instrument. The control point ofsuch an instrument is adjustable periodically to meet varyingconditions, and it is highly essential that the apparatus be so arrangedthat the recording instrument shall give an accurate indication of whattemperature the plant is delivering, that is, the recording device mustrespond accurately to adjustments made in the control point of thethermostat and by mechanism which is operative automatically in responseto changes in that control point and without an inspection or checkingof any other instrument.

Pressure from main line 6 is delivered through relay C to thethermostat, which thermostat in turn varies the reading of the recordinginstrument and provides means for readjusting the instrument 0 inaccordance with changes in the adjustment of the thermosta Theinstrument B comprises a base I for supporting the valve mechanism andincludes a thermostatic couple made up of arelativelyexpansibletubel,flxed atoneendinthebasel and capped at theother end at 9, and a relatively inexpansible rod II. The forward end ofrod i2 is guided by the member I: through which it may slidelongitudinally as the member I expands and contracts with changes intemperature. A compression spring ll reacts against acollar litoholdtherear end ofrod l2 against the cap I.

Pivoted at Ii on member I! is a yoke or lever l6 drawn toward the base 1by a spring H. Member It carries a leak port ll cooperating with amovable lid is and connected through pipe II to the controlling chamber22 of relay I. The lid I l, which is pivoted at II to the member I,which forms a to the member part of a yoke 28 pivoted at II Ii. This arm23 carries an adiusting screw 21 which contacts with one end of the rodi2 and is biased into contact with the end of that rod by a spring 25connected between the yoke 26 and the member II. The arm 23 cooperateswith a stop pin adjustably mm in a slotted arm forming a part of theleak port lid ll. The setting of the adjusting screw 21 is indicated bya pointer 46 cooperating with a scale 41 carried on the yoke II.

In operation with a given control point adjnstment, movement of thethermostat will vary the position of lid is with respect to leak port itand thus establish varying pressures in controlling chamber 22 of relay6. When, however, the control or setting point of the instrument is tobe changed, it is necessary to perform other adjustments and this isprovided for by means of a pneumatic motor operating through a shiftablecam to vary the relation of the leak port II with respect to its lid it.The mechanism for performing this adjustment comprises a diaphragm cell28 to and from which pressure iiuid is admitted and exhausted bysuitable means such as a pilot line is connected to both the responds topivotal movement of arm 28 7 recorder and the readjusting instrument A.The cell It is carried by the base I and reacts against a plate I!forming one arm of a bell crank lever. the other arm of which appears at32. The motion of plate II in both directions is limited by a stop screw38 which is adjustable to vary the position of its head with respect tothe fixed stops 33a and lib. The bell crank is pivoted at 34 and itsplate II is biased towards the base I by a tension spring 35 attached atone end to the base, and at the other end to an arm which is attached tothe plate 3| and carries an adjusting screw 36 for varying the tensionof spring 36.

Arm 32 carries pivoted to it at 31 a cam block a. By tilting block I. onits pivot 31, the 0b-- liquity of the cam face to the path of pivot 11may be varied, and this adjustment is fixed by clamping an arm isintegral with block it in a slot in sector plate 4| by a screw 42. Thefront or cam face of block it reacts against thrust screw it mounted ina lug 44 carried by member l6. Screw 33 with its associated lugs limitthe motion of the bell crank but the obliquity of the cam face of block38 determines how far member I will be caused to shift by such motion ofthe bell crank.

The instrument just described is capable oi producing varying branchline pressure in accordance with varying conditions, be theytemperature, pressure, humidity, or the like. The branch line pressurevariations are transmitted through branch line 2| connected with leakport II, and it is an indication of these pressure variations which areto be recorded on the instrument C. Although this instrument might beconnected directly to the instrument B, it will inmost instances benecessary to provide an intermediate relay in order to get sumcientpower to. operate the recording mechanism. In the lilustration such arelay has, therefore, been included in the form of relay 6 embodyingsubstantially the mechanism described and claimed in Otto Patent N1,500,260, granted July 8,

- For purposes of the present specification, a brief description of therelay 8 will be suflicient. It may conveniently comprise a base llcarrying a body including two diaphragms I8 and ll of unequal areas andhaving a space between them vented at Ii to atmosphere. The chamber 22formed between the outermost diaphragm l8 and the cover 52 of theinstrument is connected to the branch line 2| of instrument B as alreadynoted. A hub 53 carried jointly by the two diaphragms and forming acommunication 54 between them and the inner chamber 55, controls theflow of air from this chamber to the space between the diaphragms andthence to atmosphere. The inner end of the hub 53 also acts against aconical admission and exhaust valve 56 of conventional type biased by aspring 5! to the right hand position in which it seats at 58. Thechamber 59 formed adjacent the enlarged portion of the valve isconnected to line 5 from which it receives main line pressure.

The chamber is connected through duct I with pipe line 62. It will beapparent that since the diaphragms 4B and 49 are of diflerent crosssectional areas, the variations in pressure occurring in chamber 22 andresulting from varicording instrument. When the pressure within chamber22 is low enough to cause hub II to 1y include the usual movable chart88 having a move away from the valve 58,"pressure from chamber 55 willexhaust rapidly to atmosphere through openings 5| and thus facilitatedischarge of air upon a return motion of the pneumatically operatedrecording mechanism now to be described. j

The recording instrument C may convenientcooperating recording pen arm64 pivoted at 65 and adapted for actuation through arm 68 connected tobellows 61. The bellows 61 is carried by an arm 88 and is supplied withpressure fluid from line 62 to which it is connected, the pressure beingindicated by a gauge 68. The arm 68 pivoted at II is biased to its righthand position ly as follows: With the bellows ll deflated and arm 68biased to its extreme .right hand position by spring 12, variations inpressure in line 62 will expand or contract bellows 61, transmittingthose variations tov the recording pen arm 64 and'thus varying therecord produced onthe chart 68.

When the control or setting point of instrument B is varied by changingthe pressure in pilot line 29 and hence in diaphragm cell 28, this samepressure will be communicated through line 15 to bellows M to change theinitial position of arm,

88 and thus the base of bellows 81 which it carries. In this way, thestartingpoint of pen arm 64 will be varied to correspond to eachreadjustment of instrument B and will produce all further indications inthe normal manner as the pressure varies in line 62.

As pointed out above, it will be found convenlent in many installationsto locate the setting point control instrument at a point remote notonly from the instrument B, but likewisefrom the recorder C. With suchan arrangement, the

- instrument A can be adjusted manually to transmit predeterminedvarying pressures through pilot line 29, and thus to change the settingof instrument B as well as to vary the pressure in bellows 14 associatedwith instrument C. Although the instrument A may take various forms, onesatisfactory and convenient structure will be described for purposes ofillustration.

Since the instrument A consists primarily of manually operable mechanismfor establishing predetermined pilot line pressures from a constantpressure main line supply, it is connected both to the pilot line 28 andto the main line 5. It may comprise a housing including abase I1 and abody 83 connected at 18 to main air supply 5. A spring biased inletvalve 18 disposed in chamber 8| in the base controls the supply of airto the branch line 29 connected to a chamber 82. This valve hasa conicalface whichmay seat at 88 to isolate the chamber 8| andit may also seatagainst and seaLan opening 86 in a hub 85, later to be described.

Interposed between the base 11 and the body 88 is a diaphragm 84 whichdefines the chamber 82 already mentioned. The diaphragm 84 carries a hubcontaining an exhaust channel 86 communicating with the chamber 8| andthe space above the diaphragm 84. The space above the diaphragm isvented to atmosphere at 81 and contains a. spring 88 having its lowerend resting on a spring seat 88 rigidly connected to the hub 85. Restingagainst the top of spring 8.8 is a second seat 8| carrying a pin 82 engang a rotatable. cam 88. Cent 98 is carried by shaft 88 mounted in thehousing 88 and having a hand wheel 85 by means of which it may beactuated to vary the loading of spring 88. A pointer 85, movabie'withthe hand wheel, cooperates with a fixed scale 81 to indicate whatpressure is established in the pilot line by varying the loading of thespring. 1

The operation of the'device A is as follows: Whenever valve I8 is movedoff its seat by loading of spring 88, flow of air from chamber 8|throughopening 88 is prevented by the valve 18.

Main line air then flows from pipe 18 to chamber 8| and aroundthe valve18 into the chamber 82 to the pilot line 28. This flow continues untilthe pressure established in chamber '82 is sufficient 'to balance theloading of spring 88 at which time the hub 85 is moved out of engagementwith the valve 18,'and anyffurther pressure supplied to chamber 82.isdissipated through opening 86 to atmosphere at 81 to maintain thepressure in chamber 82 and pilot line 29 at the value determined by theloading of spring 88. When the diaphragm 84 becomes balanced and 'bydissipation of any excess fluid through opening 86, pressure in chamber82 becomes established at the selected value and valve 19 engages itsseat 88 to prevent further entry of fluid into chamber 82 until suchtime as further adjustment may be made in the loading of spring 88, thatis chamber 8| becomes isolated from chamber 82 and no fluid can escapearound the valve 19. The parts are so arranged that when diaphragm 84occupies its normalposition, valve 18 engages the seat in the hub 85 toprevent loss of fluid. Whenever the pressure of spring 88 predominatesover that of the.fluid in chamber 82, opening-86 is sealed by valve .19'andchambers 8| and 82 are in 1 free communication. Whenever pressure inchamber 82 predominates overthat of spring 88, valve 18 seats at 88 butis out of engagement with hub 85 to dissipate pressure in chamber 82.The operation of the complete system shown in Fig. 1 may be statedbriefly as follows: The

instrument B controls the conditioning apparatus in accordance with thesetting'po-int established, and pressure supplied tothe instrument Cthrough branch line 62 gives a record of the conditions which are beingestablished by'the.

instrument B. Whenever it is desired to change the setting point ofinstrument B, hand wheel is rotated to load the spring 88 and thusestablish in the pilot line 28 any desired pressure to produce desiredresponse of instrument B.

Since the pilot line '28not only operates the diaphragm cell 28 ininstrument B, but also supplies pressure through line 15 to bellows H,the parts of instrument C are readjusted in accordance with the newsetting or control point of instrument B, and hence instrument Caccurately records conditions which are being established I orcontrolled by instrument B regardless of what setting point is chosen,and in exact accordance with those conditions no matter what the manualsetting of instrument A may be. In other words, the single meanscomprising the device 'A accurately adjusts theinstrument B, and at thesame time readjusts relatively the scale and pointer of instrument 0 toensure an accurate response of instrument 0 at all times.

In Fig; 1, it has been indicated that the device A is located at a pointremote from both the instruments B and C, but under certain conditionsit may be desirable to locate the instrument A in proximity to theinstrument C. Consequently, by such an arrangement the instrument A maybe manually adjusted to establish a predetermined pressure in line 29,the instrument C being readjusted at the same time that instrument B hasits setting point changed. Such an arrangement is shown in Fig. 2 of thedrawings.

Referring to Fig. 2 of the drawings, the instruments A, B and C andtheir connections are substantially those which have already beendescribed. Consequently, reference characters in Fig. 2 are duplicatedwhere the parts correspond to those already described. The control ofinstrument B with its associated relay 6 takes place in the manner whichhas already been set forth, but the readjustment of instrument C is notperformed pneumatically, but mechanically. The shaft 94 which carriesthe handwheel 95 and its cooperating pointer, also carries a gear 98adapted to mesh with the teeth on a curved sector plate iiil, carried bythe lower end of depending arm 99. The arm 99 forms the base for bellows6'1 and, with the exception that it is provided with the gear sector,may have substantially the form of the arm 68 of Fig. 1. As aconsequence of this arrangement, any movement of handwheel 95 to varythe loading of spring .8 simultaneously moves the sector plate ifli tothe right or to the left to vary the initial or starting position of arm89. In other words, any movement of handwheel 95 to change the settingpoint of instrument 3, simultaneously readjusts the pen arm 64 withrespect to its chart 63. Inasmuch as the variation in the control pointof instrument B takes place in the manner already described inconnection with Fig. 1, repetition is believed to be unnecessary.

A further embodiment of the invention which may, under somecircumstances, be desirable is that shown in Fig. 3 wherein theinstrument A is shown directly connected to the instrument B, theinstruments A and B being remotely located with respect to instrument C.

In Fig. 3, the arrangement of the recording instrument C is the same asthat described with respect to Fig. 1, and the pen arm and chart havetheir positions readjusted each time that the control point ofinstrument B is varied. The instrument A is, however, geared directly tothe dial screw of instrument B, and acts by a direct mechanicalconnection to change the setting or control point of the instrument.

In Fig. 3, the reference characters used in connection with Fig. 1 havebeen repeated where appropriate. Further description of instruments Aand C will be unnecessary except to say that the shaft 94 of instrumentA carries a gear 98 as in Fig; 2. This gear meshes with a pinion Hi2carried by the adjusting screw 21 of instrument B. Whenever handwheel 95is rotated to change the loading of spring 88 ofdinstrument A, the gearand pinion 98 and I02 change the setting or control point of instrumentB by direct mechanical connection while the readjustment between the penarm and chart of instrument C is performed pneumatically as in Fig. 1.

In the form of the invention shown in Fig. 3, illustration of the relaydevice 6 has been omitted and it is to be understood that it may or maynot beincluded, depending upon the amount of power required to operatethe instrument C.

2,aos,oso

The operation of the system shown in Fig. 3 will be apparent withoutfurther explanation.

Although it is known in the prior art to provide pneumatic telemeteringsystems, no simple and precise mechanism capable of giving accu- It isto be understood that although particular instruments have beenillustrated by way of example, equivalent types of instrument may beused to produce the result contemplated.

' What is claimed is:

1. In a pneumatic telemetering system a source of pressure fluid; apneumatic controlling device connected to said source and adapted todeliver pressure variable relative to a control point, said devicehaving an adjustable control point determining the point at which saidpressure varies; a pneumatic recording device arranged to recordquantitatively the variable pressure delivered by said device and havingrelatively adjustable indicating elements; and means for simultaneouslyadjusting the control point of said device and readjusting saidindicating elements relatively, to make the indications of saidrecording device correspond to the control point of said controllingdevice.

2. In a. pneumatic telemetering system a source of pressure fluid; apneumatic controlling device connected to said source and adapted todeliver pressure variable relative to a control point, said devicehaving an adjustable control point determining the point at which saidpressure varies: a pneumatic recording device arranged to recordquantitatively the variable pressure delivered by said pneumaticcontrolling device and having a relatively adjustable scale and pointer;and pneumatic means for simul adjusting the control point of saidcontrolling device and readjusting said scale and pointer relatively tomake the indications of said recording device correspond to the controlpoint of said controlling device.

' 3. In a pneumatic telemetering system a source of pressure fluid; a.pneumatic controlling device connected to said source and adapted todeliver a secondary pressure which is variable relative to a controlpoint and as a function of an atmospheric condition to be controlled,said device having an adjustable control point determining the point atwhich said pressure varies; means for varying said condition in responseto variations in said secondary pressure; a pneumatic recorder arrangedto indicate said condition quantitatively in response to variations insaid secondary pressure and having relatively adjustable indicatingelements; and means for simultaneously adjusting the control point ofsaid device and readjusting said indicating elements relatively to makethe indications of said recorder correspond to the control point of saiddevice.

4. In a pneumatic telemetering system a source of pressure fluid; apneumatic controlling device connected to said source and adapted todeliver aaot cao a secondary pressure which is variable relative to acontrol point and as a function of an atmospheric condition to becontrolled, said device having an adjustable control point determiningthe point at which said pressure varies; means for varying saidcondition in response to variations in said secondary pressure; apneumatic recorder arranged to indicate said condition quantitatively inresponse to variations in said secondary pressure and having arelatively adjustable scale and pointer; and pneumatic means forsimultaneously adjusting the control point of said device andreadjusting said scale and pointer relatively to make the indications ofsaid recorder correspond to the control point of said device. v

5. In a pneumatic telemetering system a source of pressure fluid; apneumatic controlling device connected to said source and adapted todeliver pressure variable relative to a control point, said devicehaving an adjustable control point determining the point at which saidpressure varies; a pneumatic recorder arranged to indicatequantitatively the variable pressure delivered by said device and havingrelatively adjustable indicating elements; and pressure adjusting meanslocated at a point remote from both said controlling device and saidrecorder adjusting the control point of said device and readjusting saidindicating elements relatively to make the recorder indicationscorrespond to the device control point.

6. In a pneumatic telemetering system a source justing forsimultaneously of pressure fluid; a pneumatic controlling instrumentconnected to said source and adapted to deliver pressure variablerelative to a control point, said instrument having an adjustablecontrol point determining the point at which said pressure varies; apneumatic recorder arranged to record quantitatively the variablepressure delivered by said device and having relatively adjustableindicating elements; and pressure admeans mechanically connected withsaid recorder for simultaneously adjusting the control point of saidinstrument and readjusting said indicating elements relatively to makethe recorder indications correspond to the instrument control point.

'7. In a pneumatic telemetering system a source of pressure fluid; apneumatic controlling instrument connected to said source and adapted todeliver pressure variable relative to a control point, said instrumenthaving an adjustable control point determining the po' t at which saidpressure varies; a pneumatic recorder arranged to indicatequantitatively the variable pressure delivered by said device and havingrelatively adjustable indicating elements; and pressure adjusting meansmechanically connected with said controlling instrument forsimultaneously adjusting the control point of said instrument andreadjusting said indicating elements relatively to make the recorderindications correspond to the instrument control point.

CARL A. O'I'IO.

